Snowmobile with vertically adjustable skis

ABSTRACT

In a snowmobile of the type including rear endless track drive means and a pair of forward opposite side dirigible skis the skis are oscillatably supported from the lower free piston rod end portions of a pair of hydraulic cylinders for angular displacement relative to the cylinders about horizontal transverse axes. Suitable structure is provided for preventing rotation of the piston rod portions of the cylinders relative to the cylinder portions thereof and the cylinder portions are supported from the snowmobile chassis for angular displacement about their longitudinal axes whereby steerage of the snowmobile may be affected in the usual manner. By supporting the skis from the extendable and retractible piston portions of the cylinders the snowmobile may be leaned to the inside of a turn and in an uphill direction when traversing a slope to thereby increase the stability of the snowmobile.

United States Patent 91 Rogerson [451 Oct. 16, 1973 1 SNOWMOBILE WITI-IVERTICALLY ADJUSTABLE SKIS [76] Inventor: John R. Rogerson, Main St. Box10,

Leonardville, New Brunswick, Canada [22] Filed: Mar. 8, 1972 [21] Appl.No.: 232,778

Primary Examiner-Richard J. Johnson AttorneyHarvey B. Jacobson [5 7]ABSTRACT In a snowmobile of the type including rear endless track drivemeans and a pair of forward opposite side dirigible skis the skis areoscillatably supported from the lower free piston rod end portions of apair of hydraulic cylinders for angular displacement relative to thecylinders about horizontal transverse axes. Suitable structure isprovided for preventing rotation of the piston rod portions of thecylinders relative to the cylinder portions thereof and the cylinderportions are supported from the snowmobile chassis for angulardisplacement about their longitudinal axes whereby steerage of thesnowmobile may be affected in the usual manner. By supporting the skisfrom the extendable and retractible piston portions of the cylinders thesnowmobile may be leaned to the inside of a turn and in an uphilldirection when traversing a slope to thereby increase the stability ofthe snowmobile.

5 Claims, 6 Drawing Figures PAIENTEDMHGEUS I 3.765498 SHEEI 3 BF 2 ResSNOWMOBILE WITH VERTICALLY ADJUSTABLE SKIS When snowmobiling it isimportant to bear in mind that a snowmobile has a relatively high centerof gravity and that sharp turns must be negotiated at slow speeds unlessthe operator and the passenger or passengers on the snowmobile leanexcessively to the inside of the turn. In addition, steep slopes may notbe traversed without the operator and passenger or passengers leaning inthe uphill direction. While this mandatory method of operation of asnowmobile need not be resorted to frequently during casual operation ofa snowmobile, more serious operation of snowmobiles involves turning athigh speeds and may often require traversing very wide and steep slopes.Therefore, the operator and passenger or passengers of a snowmobile canbe seriously inconvenienced by having to repeatedly lean in the uphilldirection for long periods of time while traversing a wide slope.

The main object of this invention is to provide a snowmobile of the typeincluding a pair of opposite side forward dirigible skis with the skissupported from the snowmobile chassis by means of the extendable pistonrod portions of hydraulic cylinders whereby the skis may be individuallyvertically shifted relative to the snowmobile chassis.

Another object of this invention, in accordance with the immediatelypreceding object, is to provide a snowmobile modified in accordance withthe present invention in a manner such that normal steerage of thesnowmobile is unchanged.

Still another object of this invention is to provide a mountingstructure in accordance with the preceding objects and which may bereadily added to existing snowmobiles as well as incorporated into themanufacture of new snowmobiles.

A final object of this invention to be specifically enumerated herein isto provide a snowmobile in accor dance with the preceding objects whichwill conform to conventional forms of manufacture, be of simpleconstruction and easy to operate so as to provide a device that will beeconomically feasible, long lasting and relatively trouble free inoperation.

These together with other objects and advantages which will becomesubsequently apparent reside in the details of construction andoperation as more fully hereinafter described and claimed, referencebeing had to the accompanying drawings forming a part hereof, whereinlike numerals refer to like parts throughout and in which:

FIG. I is a side elevational view of a conventional form of snowmobilemodified in accordance with the present invention;

FIG. 2 is a front elevational view of the snowmobile with the front skisthereof vertically spaced relative to the snowmobile chassis in a mannerso as to position the snowmobile in an upright position when on levelground;

FIG. 3 is a front elevational view of the snowmobile illustrating themanner in which one of the front skis thereof may be displaceddownwardly relative to the snowmobile chassis in order to incline thesnowmobile relative to the horizontal while on horizontal ground;

FIG. 4 is a fragmentary top plan view of the front ski assemblies of thesnowmobile and the steering apparatus connected thereto with thehydraulic circuit of the 2 ski supporting hydraulic cylinderdiagrammatically illustrated;

FIG. 5 is an enlarged longitudinal sectional view taken substantiallyalong the longitudinal center lines of one of the cylinders; and

FIG. 6 is an enlarged sectional view similar to FIG. 5 but illustratinga modified form of cylinder.

Referring now more specifically to the drawings the numeral 10 generallydesignates a conventional form of snowmobile including a rear endlessdrive track assembly referred to in general by the reference numeral 12and a pair of front ski assemblies referred to in general by thereference numeral 14.

The ski assemblies 14 each consist of a ski member 16 having a forwardlyand upwardly curving front end 18 and provided with a downwardly openingbowed spring 20 having its opposite ends connected to the upper surfaceof the ski member 16 as at 22 and 24. The midportion of the spring 20includes a pair of upstanding opposite side mounting ears 26 providedwith aligned bores 28. Back ski assembly 14 additionally includes ahydraulic cylinder referred to in general by the reference numeral 30consisting of a cylinder portion 32 disposed in upstanding position andopen at its lower end. The upper end of the cylinder portion 32 definesa smooth longitudinal and cylindrical bore 34 and the lower end of thebore 34 opens into a splined counterbore 36 extending through the lowerportion of the cylinder portion 32. The lower end of the counterbore 36opens outwardly of the bottom of the cylinder portion 32 and the upperend of the bore 34 is closed by means of an upper end plate 38 securedover the upper end of the cylinder portion 32 by means of removablefasteners 40. The end plate 38 is provided a central opening 42 in whichan inlet fitting 44 is threadedly secured.

The upper smooth cylindrical end 46 of an upstanding piston rod portion48 is slidingly telescoped into the bore 34 and has an-upper endcircumferential groove 50 formed therein inwhich a sealing ring 52 isseated. The lower end 54 of the piston rod portion 48 is splined as at56 and keyed into the splined counterbore 36.

The lower end of each piston rod portion 48 projects downwardly from thelower end of the corresponding cylinder portion 32 and has a transversesleeve 58 secured thereto receivable between the corresponding aperturedmounting ears 26. A pivot fastener 60 is secured through each pair ofapertured mounting ears 26 and the corresponding transverse sleeve 58whereby each ski member 16 is spring supported from its correspondinghydraulic cylinder for up and down shifting with the correspondingpiston rod portion 48 relative to the associated cylinder portion 32.

Each hydraulic cylinder 30 is supported from the chassis of thesnowmobile 10 by means of vertically spaced combined thrust and journalbearing assemblies 62 and accordingly, the ski members 16 are mounted indirigible fashion for steering the snowmobile 10, as is conventional.

Each of the cylinder portions 32 has one end of a steering arm 64mounted thereon by means of a setscrew 66 and the free ends of thesteering arms 64 have remote ends of a pair of tie rods 66 pivotallysecured thereto. The remote ends of the tie rods 66 are pivotallyattached to a steering arm 68 carried by the steering column 70 of thesnowmobile l0 and the column 70 is supported from the snowmobile chassisby means of a conventional bearing assembly 72.

The upper end of the steering column 70 is provided with theconventional handle bar assembly 74and thus it may be seen that thesnowmobile 10 may be steered in the conventional manner. However, withattention now invited more specifically to FIG. 4 of the drawings, itmay be seen that there is pro-vided a hydraulic pump 76 to which a pairof pressure lines 78 are connected. The ends of the lines 78 remote fromthe pump 76 open into the inlet ports of a pair of manually actuatablevalves 80 which are of the two way type. A combined pressure and returnline 82 extends between each valve 80 and the corresponding inletfitting 44 and a pair of return lines 84 extend from the valves 80 tothe reservoir 86 from which hydraulic oil is supplied to the pumpthrough a supply line 88. I

The pump 76 may be driven from the engine (not shown) of the snowmobilel and the valves 80 may be provided with actuators 90 and positioned onopposite sides of the snowmobile for foot actuation in the mannerillustrated in FIG. 1 of the drawings. in addition, the pump 76 may beof the manually operable type, although if a manual pump is utilizedvertical adjustment of the ski assemblies 14 would be substantiallylimited to adjustment of the ski assemblies for the purpose oftraversing a wide steep slope inasmuch as there would not be sufficienttime in which to manually generate sufficient hydraulic pressure inorder to execute a sudden turn with the snowmobile tilted to the insideof the turn. The pump 76 may be of any conventional type such as thatutilized for power steering purposes on conventional motor vehicles andthe valves 80 may be of the type wherein the actuators 90 thereof may bedepressed on one occasion to open the lines 78 to the lines 82 and on asubsequent occasion to open the lines 82 to the lines 84. Of course, itis to be appreciated that the valves 80 are actuatable independently ofeach other.

With attention now invited more specifically to FIG. 6 of the drawingsthere may be seen a modified form of hydraulic cylinder referred to ingeneral by the reference numeral 30. The hydraulic cylinder 30' is quitesimilar to the hydraulic cylinder 30 and differs from the latter only inthat instead of the piston rod portion 48' thereof being splined and thecylinder portion 32' thereof being provided with splined counterbore,the piston rod portion 32' is provided with a key 36' and the piston rodportion 48 is provided with a keyway 56' in which the key 36' isslidingly received. The foregoing is considered as illustrative only ofthe principles of the invention. Further, since numerous modificationsand changes will readily occur to those skilled in the art, it is notdesired to limit the invention to the exact construction and operationshown and described, and accordingly all suitable modifications and rearground engaging drive means supported from said chassis, the forward endportion of said chassis including laterally spaced opposite side skimeans, support means supporting said ski means from said chassis forlike angular displacement about upstanding axes and independent shiftingin up and down directions relative to said chassis, steering meansconnected between said chassis and said ski means for selectivelyoscillating said ski means in unison about said axes, force meansconnected between each of said ski means and said chassis forselectively downwardly shifting said ski means relative to said chassis,said support means including a pair of upstanding fluid motors eachincluding a cylinder portion and a piston rod portion extendible andretractable relative to said cylinder portion, said cylinder portionsbeing journaled from said chassis for oscillation about said upstandingaxes and against axial shifting relative to said chassis, said pistonrod portions being extendible and retractable relative to the lower endsof said cylinder portions, said ski means being supported from the lowerend portions of said piston rod portions, said steering means beingoperatively connected between said cylinder portions and saidchassis-for selectively oscillating the former relative to the latterabout said axes, said steering means including means slidably keyingsaid piston rod portions to the corresponding cylinder portions foroscillation therewith, said force means comprising fluid inlet andoutlet means communicating the interiors of the upper end portions ofsaid cylinder portions with the exteriors of said cylinder portions,whereby fluid under pressure may be supplied to and vented from theinterior of each cylinder portion so as to downwardly extend and allowupward retraction of, respectively, the corresponding piston rodportion.

2. The combination of claim 1 wherein said means keying said piston rodportions to said cylinder portions comprise splined connections betweensaid piston rod and cylinder portions.

3. The combination of claim 1 wherein said means keying said piston rodportions and cylinder portions together comprises a key carried by oneof said portions and a keyway formed in the other of said portions inwhich said key is slidably received.

4. The combination of claim 1 wherein each of said ski means comprises agenerally horizontally disposed ski member including a forwardly andupwardly curvsprings, the midportions of said leaf springs beingsupequivalents may be resorted to, falling within the scope ported fromthe lower ends of said shaft portions and the free ends of said leafsprings being secured to said ski members at points spacedlongitudinally therealong.

1. In combination, a snowmobile including a chassis, rear groundengaging drive means supported from said chassis, the forward endportion of said chassis including laterally spaced opposite side skimeans, support means supporting said ski means from said chassis forlike angular displacement about upstanding axes and independent shiftingin up and down directions relative to said chassis, steering meansconnected between said chassis and said ski means for selectivelyoscillating said ski means in unison about said axes, force meansconnected between each of said ski means and said chassis forselectively downwardly shifting said ski means relative to said chassis,said support means including a pair of upstanding fluid motors eachincluding a cylinder portion and a piston rod portion extendible andretractable relative to said cylinder portion, said cylinder portionsbeing journaled from said chassis for oscillation about said upstandingaxes and against axial shifting relative to said chassis, said pistonrod portions being extendible and retractable relative to the lower endsof said cylinder portions, said ski means being supported from the lowerend portions of said piston rod portions, said steering means beingoperatively connected between said cylinder portions and said chassisfor selectively oscillating the former relative to the latter about saidaxes, said steering means including means slidably keying said pistonrod portions to the corresponding cylinder portions for oscillationtherewith, said force means comprising fluid inlet and outlet meanscommunicating the interiors of the upper end portions of said cylinderportions with the exteriors of said cylinder portions, whereby fluidunder pressure may be supplied to and vented from the interior of eachcylinder portion so as to downwardly extend and allow upward retractionof, respectively, the corresponding piston rod portion.
 2. Thecombination of claim 1 wherein said means keying said piston rodportions to said cylinder portions comprise splined connections betweensaid piston rod and cylinder portions.
 3. The combination of claim 1wherein said means keying said piston rod portions and cylinder portionstogether comprises a key carried by one of said portions and a keywayformed in the other of said portions in which said key is slidablyreceived.
 4. The combination of claim 1 wherein each of said ski meanscomprises a generally horizontally disposed ski member including aforwardly and upwardly curving forward end portion, said ski means beingsupported from the lower end portions of said piston rod portions foroscillation relative thereto about horizontal axes extendingtransversely of said piston rod portions and said ski means.
 5. Thecombination of claim 4 including a pair of generally horizontaldownwardly opening arcuate leaf springs, the midportions of said leafsprings being supported from the lower ends of said shaft portions andthe free ends of said leaf springs being secured to said ski members atpoints spaced longitudinally therealong.